Joint, more particularly for chairs, bedsteads, stretchers, or the like



C. E. E. LUNDQUIST JOINT, MORE PARTICULARLY FOR CHAIRS 2 Sheets-Shae; 2

Oct. 31, 1944.

BEDSTEADS, STRETCHERS, OR THE LIKE Filed June 2 0d. 31, 1944. CLUNDQU|$T 2,361,853

JOINT, MORE PARTICULARLY FOR CHAIRS,

' BEDSTEADS, STRETCHERS, OR THE LIKE Filed June 22v 1942 2 Sheets-Sheet1 back-rest frame and 4 a foot-rest frame.

Passes Oct. 31, 1944 JOINT, MORE PARTICULARLY FOR CHAIRS, I

BEDSTEAD S, STRETCHERS, OR THE LIKE Carl Ernst Edvard Lundquist,Stockholm, Sweden Application June 22, 1942, Serial No. 447,968 InSweden June 21, 1941' 8 Claims.

My invention relates to joints, more particularly for chairs, bedsteads,stretchers or the like.

in which members, such as the seat, back-rest,

foot-rest and the legs, are relatively rotatable and adapted to beshifted andlocked in different angular positions. joints with two ormore hub elements, which are axially movable relatively to the centre ofrota- It is known to provide such tion of the joint in a manner such asto be brought into and out of locking position by a force acting in theaxial direction. It is the main object of the invention to improvejoints of this type, so that the hub elements, even when they are notlocked, will be kept in their position with a force which doesnot causeany annoying resistance to a desired-adjustment, and which" also doesnot obstruct or impair the locking effect in the axial direction. i Y

Further-objects and advantagesof the invention will be apparent fromthefollowing description considered in connection with the accompanyingdrawings which forni a part of this specification, and of which:

Fig. 1 shows 'a side view of a frame for an adjustable chair accordingto the invention.

,Fig. 2 shows a plan view of the frame. Fig. 3 shows a side view of theframe in collapsed condition.

Fig. 4 shows a section through one of the joints of the frame to anenlarged scale. Fig. 5 shows -a portion of this joint, partly in sectionon the line V--V of Fig. 4. i

Fig. 6 is'a, section through two toothed rim on a still more enlargedscale. v

V Fig. '1 shows a portion of one of the toothed rims viewed from above.Fig. 8 shows a section through the axis of a joint according to amodified embodiment of the invention.

Fig. 9' is a Fig. 8.

In the embodiment according to Figs. .l-7, I designates two framemembers forming the seat of a chair, 2 are frames forming the legs, Sisa The frames may be made, from steel -.Dipes. -The frames 2, 3 and 4 maybe .U-shaped. The framesview taken on the line Ire- 1x of 3 and 4 may betelescoped, as at 32, to form handles so that the chair also can be usedas bedstead or stretcher.

The frames l-,- 2 and-3 and I, 2 and 4, respectively, are pivotallymounted relatively to each otherabout two shafts 8. (Fig- 4) with theaid of hub elements 8, 5 and 1 secured to the end portions of theframes. The hub elements Got the frame members I are arranged betweenthe hub elements 5, I, and the hub elements I of the frames 3 and 4 maybe located inside the hub elements 6. In the embodiment shown, thedistance between the hub elements 1 is fixed in an inward direction bymeans of aspacing piece, for

instance in the form of a sleeve 9 surrounding the shaft 8.

An operating member I0, preferabl in the locked in the desired position.The shaft 8 may be formed at the opposite end thereof with an enlargedhead l5 (Fig. 4) bearing against the outermost hub element 5. Thelocking in the axial direction therefore takes place in the two 9.Various arrangements are conceivabletoiensure effective locking againstmutual rotation between the frame members. In the embodiment shown, thehub elements are provided with toothed rims I 6 which, when theoperating member I in the turning direction.

is moved into the locking position, are caused to engage one another toensure effective lockin If the operating member" is rotated upwardlyinto the position indicated with dotted lines in Fig. 2. the hubelements are caused to slide apart, I preferably through the agency ofhelical springs tion, the hub elements are provided, according to theinvention, with brake members, which in the embodiment according toFigs; 1-7 have the form of an annular spring II. This spring is insertedinto a circular recess II in one of the hub elements and bears on theouter, preferably cylindrical peripheral portion of this recess with apredetermined initial tension acting in a radial direction. In order toproduce this radial pressure, the annular spring I2 may be provided withradial folds I! (Fig. 5). Projecting members It the base thereof (seeFig. 5). The cooperating in the foregoing embodiment.

ly cannot be rotated unless a torque overcoming the radial friction ofthe annular spring 12 on the hub elements be applied to the variousframe members. This braking moment may be simply and convenientlydetermined by means of the device shown, in a manner such that the framemembers will not be rotated relativel to each other by small forces, asfor instance by their own weight, whereas the braking moment is readilyovercome, when changing the angular position of the frame members.According to the invention, the annular spring 12 at the same time doesnot ofier any appreciable resistance to the axial locking of the hubelements of the frames to each other, as described above. Consequently,when the hub elements are moved axially toward one another, theprojecting members i3 slide freely relatively to the fold in of theannular spring. To prevent the spring i2 from being displaced out of itsproper position, two or more shoulders l4 may be provided in the centralhub element 6, adjacent the spring and distributed around the peripherythereof.

As appears from the aforesaid a shifting movement of the less 2 cannot.exert any influence on the foot-rest d, or vice versa, inasmuch as thehub elements of these members are located on opposite sides of the hubelement 6 oi the seat frame i of the chair.

The cooperating toothed rims it of the hub elements may be formed with atooth section according to Figs. 6 and '7, that is to say, the toothsection is triangular, the teeth having their apexes somewhat bevelledof! in both directions from the centre obliquely down toward the baseportion. This assures that the teeth will slide into each other withcertainty, even if for some reason or other two hub elements shouldbecome disposed somewhat eccentrically with respect to each other.

If the back-rest and the foot-rest are adjusted- .so as to lie in thesame plane as the seat, the

chair may serve as a bedstead.) If the legs are swung upwards, astretcher is obtained.

In the embodiment according to Figs. 8 and 9, the brake member 20 isadapted additionally to have the function of the spring member II Tothis end the member 20 is provided with a circular portion 2| engaging arecess 22 inone of each pair of cooperating hub members i, 6, I with apredetermined initial radial tension; The brake member 20, which may beformed as a thread with circular cross section, is at both ends of. thecircular portion 2| bent axially outwardly and radially inwardly as at23. The free end portions 24 of the member 20 are then bent backwardlyand extend obliquely to the other hub element. The c rcular portion 2|may be placed in the two outermost hub elements 5, I from which theportions 23,14 extend to the central hub element 6. Projecting members II extend from the last mentioned hub element axially on both sides ofthe central portions 23 of the brake memberil. The portions 24 of thebrake member may be bevelled over part of its length (see Fig. 8).

As in the previous embodiment. the annular portion 2| of the brakemember sets up a braking torque resisting any undesired rotation of theframe members I, 2, 3, 4 when their hub elements which is just sumcientto move the hub elements 5, .6, I out of engagement when the joint isbrought out of locking position.

The hub elements are in the embodiment ac= cording to Figs. 8 and 9 madefrom metal sheets which are pressed to the desired contour. The ends ofthe respective frame members i, 2, 8, G which latter are made from metalpipes are preferably flattened out, as at 25, to form narrow recessesadapted to receive the ends of the sheet metal hubs. The frames arethen'securecl to the hub elements as by riveting or spot welding.

Although not limited thereto the inventionis particularly adapted foreasy-chairs, stretchers, bedsteads or the like for hospitals,restinghomes, shelter-rooms, and for military medical attendance as wellas for private service, where the demands for easy transportability andmanaageability are great.

While more or less specific embodiments of the invention have beenshown, it is to be un-= derstood that the same are for purpose of illustration only, and that the invention is not to be limited thereby, butits scope is to be determined by the appended claims viewed in the lightof the prior art.

What I claim is:

1. In a rotatable joint, a plurality of elements rotatable with respectto each other about an axis of rotation, said elements having adjacentradial faces formed with axially extending interengaging projections,means for exerting an axial force on said elements for clamping saidfaces together with said projections interengaged, and friction brakingmeans for resisting relative ro= tation of said elements when saidprojections are disengaged.

2. In a rotatable joint, a plurality of elements rotatable with respectto each other about an axis of rotation; said elements having adjacentradial faces formed with axially extend ng in terengaging projections,spring means between said elements for forcing said faces apart axiallyto thereby disengage said projections. means for exerting an axial forceon said elements a ainstof said elements having an interior cylindricalsurface. a generally circular spring in frictional engagement with saidcylindrical surface, and means for anchoring said spring to the adjacentelement.

4. In a rotatable joint, a plurality of elements rotatable with respectto each other about an axis of rotation, said elements having adjacentradial faces formed with axially extending interengaging projections,means for exerting an axial force on said elements for clamping saidfaces together with said projections interengaged, one of said elementshaving, an interior cylindrical I surface, a generally circular springin frictional are out of locking position. The portions 23, 24

of=the brake member on the other hand are adapted to exercise a pressurein axial direction engagement with said cylindrical surface, and meansfor preventing relative rotation between said spring and the adjacentelement, said spring being movable axially with respect to theintmentioned means, the axial extent of said lastmentioned means beinggreater than that of said spring by an amount at least as great as therelative axial displacement of said elements between engaged anddisengaged positions of said projections.

5. In a rotatable joint, a plurality of elements rotatable with respectto each other about an axis of rotation, said elements having adjacentradial faces formed with axially extending interengaging projections,means for exerting an axial force on said elements for clamping saidfacestogether with said'projections interengaged, one of said elementshaving an interior cylindrical surface, a generally circular spring infrictional engagement with said cylindrical surface, said spring beingformed with folds extending inwardly in generally radial directions, andprojections extending from the adjacent element and engaging said foldsto anchor saidspring against rotation with respect to said adjacentelement.

6. In a rotatable joint, a plurality of elements rotatable with respectto each other about an axis of rotation, said'elements having adjacentradial faces, triangular teeth extending radially along and axially fromsaid faces, the adjacent edges of the apexes of said teeth beingbeveled, means for exerting an axial force on said elements for clampingsaid faces together with said teeth interengaging, and friction brakingmeans for re- '1. In a rotatable joint, a plurality of elementsrotatable with respect to each other about an axis of rotation, saidelements having adjacent radial faces formed with axially extendinginterengaging projections, one of said elements having an interiorcylindrical surface, a spring having a generally circular portionexpanding into frictional contact with said cylindrical surface andhaving'an axially extending portion anchored to and expanding againstthe adjacent element for urging said radial faces apart axially tothereby disengage said projections, and means for exerting an axialforce on said elements against the force exerted by the axiallyextending portion of said spring for clamping said faces together withsaid projections interengaged.

8. In a folding chair, a seat member, a leg member and a rest member,elements secured to each of said members and rotatable with respect toeach other about an axis of rotation, the element which is secured tosaid seat member being between the other two elements, said elementshaving adjacent radial faces formed with axially extending interengagingprojections, means for exerting an axial force on said elements forclamping said faces together with said projections interengaged, andfriction braking means anchored against rotation to the central elementand frictionally engaging the other elements for resisting relativerotation of said elements when said projections are disengaged.

CARL ERNST EDVARDLUNDQUIST.

